Extreme ultraviolet exposure apparatus and method, and method of manufacturing semiconductor device by using the exposure method

ABSTRACT

Extreme ultraviolet (EUV) exposure apparatuses and methods, and methods of manufacturing a semiconductor device by using the exposure method, which minimize an error caused by a mirror in an EUV exposure process to improve an overlay error, are provided. The EUV exposure apparatus includes an EUV source configured to generate and output EUV, first illumination optics configured to transfer the EUV to an EUV mask, projection optics configured to project the EUV, reflected from the EUV mask, onto an exposure target, a laser source configured to generate and output a laser beam for heating, and second illumination optics configured to irradiate the laser beam onto at least one mirror included in the projection optics.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.16/406,513, filed on May 8, 2019, which claims the benefit of KoreanPatent Application No. 10-2018-0124576, filed on Oct. 18, 2018, in theKorean Intellectual Property Office, the disclosure of each of which isincorporated herein in its entirety by reference.

BACKGROUND

The inventive concepts relate to exposure apparatuses and/or exposuremethods, and more particularly, to an exposure apparatuses and/ormethods using extreme ultraviolet (EUV).

Recently, as a semiconductor circuit line width becomes finer, a lightsource having a shorter wavelength is needed. For example, EUV is beingused as an exposure light source. Due to an absorption characteristic ofEUV, a reflective EUV mask is being used in an EUV exposure process.Also, illumination optics for transferring EUV to an EUV mask andprojection optics for projecting EUV reflected from the EUV mask onto anexposure target may each include a plurality of mirrors. As a technicallevel of an exposure process increases progressively, a small erroroccurring in the EUV mask or the mirrors may cause a severe error informing a pattern on a wafer.

SUMMARY

The inventive concepts provide extreme ultraviolet (EUV) exposureapparatuses, EUV exposure methods, and/or methods of manufacturing asemiconductor device by using the exposure method, which mitigate orminimize an error caused by a mirror in an EUV exposure process toreduce an overlay error.

According to an example embodiment of the inventive concepts, an extremeultraviolet (EUV) exposure apparatus includes an EUV source configuredto generate and output EUV, first illumination optics configured totransfer the EUV to an EUV mask, projection optics configured to projectthe EUV reflected from the EUV mask onto an exposure target, a lasersource configured to generate and output a laser beam, and secondillumination optics configured to irradiate the laser beam onto at leastone mirror included in the projection optics.

According to an example embodiment of the inventive concepts, an extremeultraviolet (EUV) exposure apparatus includes an EUV source configuredto generate and output EUV, first illumination optics configured totransfer the EUV to an EUV mask, projection optics configured to projectthe EUV reflected from the EUV mask onto an exposure target, a stageconfigured to receive the exposure target thereon, and laser apparatusconfigured to generate a laser beam, and irradiate the laser beam ontoat least one mirror included in the projection optics for heating the atleast one mirror.

According to an example embodiment of the inventive concepts, an extremeultraviolet (EUV) exposure method includes generating and outputting, byusing an EUV source, EUV, transferring, by using first illuminationoptics, the EUV to an EUV mask, projecting, by using projection optics,the EUV reflected from the EUV mask onto an exposure target, generatingand outputting, by using laser apparatus, a laser beam, forming, byusing second illumination optics, an illumination shape of the laserbeam, and irradiating the laser beam having the illumination shape ontoat least one mirror included in the projection optics.

According to an example embodiment of the inventive concepts, a methodof manufacturing a semiconductor device includes generating andoutputting EUV by using an extreme ultraviolet (EUV) source,transferring, by using first illumination optics, the EUV to an EUVmask, projecting, by using projection optics, the EUV reflected from theEUV mask onto a wafer, the wafer being an exposure target, generatingand outputting, by using laser apparatus, a laser beam, forming, byusing second illumination optics, an illumination shape of the laserbeam, irradiating the laser beam having the illumination shape onto atleast one mirror included in the projection optics, patterning thewafer, and performing a subsequent semiconductor process on the wafer.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the inventive concepts will be more clearlyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is a conceptual view illustrating an EUV exposure apparatusaccording to an example embodiment;

FIGS. 2A and 2B are cross-sectional views for describing an overlayerror;

FIGS. 3A to 3C are conceptual views for describing overlay components;

FIGS. 4A and 4B are a vector display diagram and a graph for describinga K13 component of an overlay error, respectively;

FIGS. 5A and 5B are a conceptual view showing a relationship between aK13 component of an overlay error and residual X and a graph showing arelationship between the K13 component and a residual budget,respectively;

FIG. 6 is a graph showing a K13 component variation of an overlay errorwith respect to a wafer, based on a progress of an exposure process;

FIGS. 7A and 7B are graphs showing an illumination shape of EUV by anEUV mask, a shape of EUV irradiated onto a mirror, and a temperatureprofile corresponding thereto;

FIGS. 8A to 8D are conceptual views of optical devices included in asecond illumination optics in the EUV exposure apparatus of FIG. 1;

FIGS. 9A to 9C are conceptual views showing an illumination shape of alaser beam based on processing by a second illumination optics;

FIGS. 10A to 10D are conceptual views for describing the principle ofheating a mirror with a laser beam in the EUV exposure apparatus of FIG.1;

FIGS. 11 and 12 are flowcharts illustrating procedures of an EUVexposure method according to some example embodiments; and

FIG. 13 is a flowchart illustrating a procedure of a method ofmanufacturing a semiconductor device by using the exposure method ofFIG. 11.

DETAILED DESCRIPTION

Hereinafter, some example embodiments will be described in detail withreference to the accompanying drawings. Like reference numerals refer tolike elements, and their repetitive descriptions will be omitted.

When the terms “about” or “substantially” are used in this specificationin connection with a numerical value, it is intended that the associatednumerical value includes a manufacturing or operational tolerance (e.g.,±10%) around the stated numerical value. Moreover, when the words“generally” and “substantially” are used in connection with geometricshapes, it is intended that precision of the geometric shape is notrequired but that latitude for the shape is within the scope of thedisclosure. FIG. 1 is a conceptual view illustrating an extremeultraviolet (EUV) exposure apparatus 100 according to an exampleembodiment. FIGS. 2A and 2B are cross-sectional views for describing anoverlay error.

Referring to FIGS. 1 to 2B, the EUV exposure apparatus 100 according tothe present example embodiment may include an EUV source 110, firstillumination optics (1st Ill Optics) 120, projection optics (Pro Optics)130, a laser source 140, second illumination optics (2nd Ill Optics)150, a wafer stage 160, and a controller 180.

The EUV source 110 may generate and output EUV L1 having a high energydensity within a wavelength range of about 5 nm to about 50 nm. Forexample, the EUV source 110 may generate and output the EUV L1 having ahigh energy density corresponding to a wavelength of 13.5 nm. The EUVsource 110 may include a plasma-based light source or a synchrotronradiation light source. Here, the plasma-based light source may denote alight source that generates plasma and uses light emitted based on theplasma. For example, the plasma-based light source may be alaser-produced plasma (LPP) light source or a discharge-produced plasma(DPP) light source. In the EUV exposure apparatus 100 according to thepresent example embodiment, the EUV source 100 may include, for example,a plasma-based light source. However, in the EUV exposure apparatus 100according to the present example embodiment, the EUV source 110 is notlimited to a plasma-based light source. In order to increase an energydensity of illumination light incident on the first illumination optics120, the plasma-based light source may include a condensing mirror suchas an elliptical mirror and/or a spherical mirror condensing EUV.

The first illumination optics 120 may include a plurality of mirrors,and may transfer the EUV L1 emitted from the EUV source 110 to an EUVmask M. For example, the EUV L1 from the EUV source 110 may be reflectedby the mirrors of the first illumination optics 120 a, and may beincident on the EUV mask M disposed on a mask supporter 165.

The EUV mask M may be a reflective mask that includes a reflectionregion and a non-reflection and/or intermediate reflection region. TheEUV mask M may include a pattern including a reflection multilayer forreflecting EUV on a substrate including a low thermal expansioncoefficient material (LTEM) such as quartz, and an absorption layerprovided on the reflection multilayer. The reflection multilayer mayhave a structure where a molybdenum (Mo) layer and a silicon (Si) layerare alternately stacked in tens or more of layers. The absorption layermay include, for example, TaN, TaNO, TaBO, nickel (Ni), gold (Au),silver (Ag), carbon (C), tellurium (Te), platinum (Pt), palladium (Pd),chromium (Cr), and/or the like. However, a material of the reflectionmultilayer and a material of the absorption layer are not limited to theabove-described materials. Here, the absorption layer may correspond tothe non-reflection and/or intermediate reflection region.

The EUV mask M may reflect the EUV L1 incident through the firstillumination optics 120 to allow the EUV L1 to be incident on theprojection optics 130. In more detail, the EUV mask M may structurizeillumination light from the first illumination optics 120 to generateprojection light based on a shape of the pattern including thereflection multilayer and the absorption layer on the substrate, and mayallow the projection light to be incident on the projection optics 130.The projection light may be structurized through at least seconddiffraction order based on the pattern on the EUV mask M. The projectionlight may be incident on the projection optics 130 while retaininginformation about a shape of the pattern of the EUV mask M, and may passthrough the projection optics 130 to form an image, corresponding to thepattern of the EUV mask M on an exposure target W. Here, the exposuretarget W may be a substrate (for example, a wafer) including asemiconductor material such as Si. Hereinafter, the exposure target Wand a wafer may be used interchangeably. Thus, reference numeral ‘W’ mayalso refer to a wafer. The exposure target W may be disposed on thewafer stage 160. The wafer stage 160 may move in an x direction and a ydirection on an x-y plane in a Cartesian coordinate system, and may movein a z direction vertical to the x-y plane. Therefore, as the waferstage 160 moves, the exposure target W may move in the x direction, they direction, and the z direction.

The projection optics 130 may include a plurality of mirrors. In FIG. 1,the projection optics 130 is illustrated as including two mirrors (forexample, a first mirror 132 and a second mirror 134), but this is forconvenience. In other example embodiments, the projection optics 130 mayinclude more mirrors. For example, the projection optics 130 may includefour to eight mirrors generally. However, the number of mirrors includedin the projection optics 130 is not limited thereto.

The laser source 140 may generate, and output a mirror-heating laserbeam L2. The laser source 140 may include, for example, an infrared (IR)laser source for generating an IR laser beam and an ultraviolet (UV)laser source for generating a UV laser beam. However, a kind of thelaser source 140 is not limited thereto. For example, in the EUVexposure apparatus 100 according to the present example embodiment,examples of the laser source 140 may include various kinds of lasersources for generating the laser beam L2 that satisfies the followingconditions. Conditions of the laser beam L2 may include a condition forapplying energy to a mirror to heat the mirror and a condition having awavelength which does not change chemical properties of a photoresist onthe exposure target W. In some example embodiments, an EUV exposureprocess may be performed along with an ArF immersion (ArFi) exposureprocess, and the laser beam L2 may not include a wavelength of EUV usedin the EUV exposure process and a wavelength of deep UV (DUV) used inthe ArFi exposure process.

The second illumination optics 150 may transfer the laser beam L2emitted from the laser source 140 to at least one mirror of theprojection optics 130. For example, the laser beam L2 of the lasersource 140 may be directly irradiated onto the first mirror 132 of theprojection optics 130 through the second illumination optics 150. Insome example embodiments, the laser beam L2 may be directly irradiatedonto another mirror, other than the first mirror 132, of the projectionoptics 130 through the second illumination optics 150.

The second illumination optics 150 may include a plurality of mirrorsand an optical device having various functions. The second illuminationoptics 150 may form an illumination shape of the laser beam L2 of thelaser source 140 by using the mirrors and the optical device. In thismanner, in the exposure apparatus 100 according to the present exampleembodiment, the second illumination optics 150 may form an illuminationshape of the laser beam L2, the laser beam L2 may be irradiated onto apartial region of, for example, the first mirror 132, and thus thepartial region of the first mirror 132 may be heated. An example wherethe second illumination optics 150 forms an illumination shape of thelaser beam L2 will be described below in more detail with reference toFIGS. 8A to 9C.

A temperature sensor 170 for measuring a temperature of a portion or anentirety of a mirror may be disposed on a rear surface of the firstmirror 132 onto which the laser beam L2 is irradiated. The temperaturesensor 170 may measure a temperature of the first mirror 132, and thusan amount of heat or energy applied to the first mirror 132 may becalculated. For example, in the EUV exposure process, the temperaturesensor 170 may calculate the first amount of energy based on the EUV L1applied to the first mirror 132, and may calculate the second amount ofenergy to be applied to the first mirror 132 by the laser beam L2 basedon the first calculated amount of energy. The temperature sensor 170 maycalculate a temperature and an amount of energy based on the EUV L1 ineach portion of the first mirror 132. Because the temperature and anamount of energy of each portion of the first mirror 132 are calculated,a region, to which energy is to be applied by the laser beam L2 of thefirst mirror 132 may be determined and the amount of energy to beapplied to the determined region may be calculated. In a case ofmeasuring temperatures of respective portions of the first mirror 132, aplurality of temperature sensors 170 may be disposed on the rear surfaceof the first mirror 132 in correspondence with the portions of the firstmirror 132, respectively.

The temperature sensor 170 has been described above as being disposedonly on the first mirror 132, but is not limited thereto. In otherexample embodiments, the temperature sensor 170 may be disposed on othermirrors of the EUV exposure apparatus 100. For example, the temperaturesensor 170 may be disposed on other mirrors of the projection optics 130and/or mirrors of the first illumination optics 120. According to anexample embodiment, the laser beam L2 may be transferred to mirrorsdisposed along a path of the laser beam L2, in addition to the firstmirror 132, and finally transferred to the photoresist on the exposuretarget W. Thus, a certain amount of energy may be applied to othermirrors, other than the first mirror 132, of the projection optics 130by the laser beam L2. Therefore, in a case where the plurality oftemperature sensors 170 are disposed on mirrors, respectively, energyapplied by the EUV beam L1 and/or the laser beam L2 may be calculated.As described above, because the laser beam L2 has to be configured notto change the chemical properties of the photoresist on the exposuretarget W, the laser beam L2 may have a wavelength that does not changethe chemical properties. For example, in a case where the photoresist onthe exposure target W chemically reacts with a wavelength of EUV and/ora wavelength of DUV, the laser beam L2 may have a wavelength other thanthe wavelength of EUV and the wavelength of DUV.

A controller 180 for controlling various operations of the EUV exposureapparatus 100 (e.g., operations of (and/or calculations for) the EUVsource 110, the first illumination optics (1st Ill Optics) 120, theprojection optics (Pro Optics) 130, the laser source 140, the secondillumination optics (2nd Ill Optics) 150, and/or a wafer stage 160) maybe included in the EUV exposure apparatus 100.

The controller 180 may be implemented with processing circuitry, such ashardware including logic circuits, a processing unit including softwareand a core executing the software, or a combination of the hardware andthe processing unit, that is configured to control some or all of, forexample, the operations illustrated in FIGS. 11-13. For example, theprocessing circuitry may include, but is not limited to, a processor,Central Processing Unit (CPU), a controller, an arithmetic logic unit(ALU), a digital signal processor, a microcomputer, a field programmablegate array (FPGA), a System-on-Chip (SoC), a programmable logic unit, amicroprocessor, or any other device capable of responding to andexecuting instructions in a defined manner.

In the EUV exposure apparatus 100 according to the present exampleembodiment, the laser source 140, the second illumination optics 150,and the temperature sensor 170 may configure laser apparatus LA forheating a mirror.

The EUV exposure apparatus 100 according to the present exampleembodiment may heat at least one mirror of the projection optics 130with the laser beam L2 by using the laser apparatus LA, therebyminimizing an overlay error caused by a mirror. Here, in the EUVexposure process, a mirror heated by the laser beam L2 of the laserapparatus LA may correspond to a mirror that causes an overlay error dueto non-uniform heating by the EUV L1. For example, a mirror heated bythe laser beam L2 of the laser apparatus LA may correspond to a mirrorassociated with a component of an overlay error incapable of beingremedied through physical actuation.

For reference, an overlay may denote a degree to which a current layercorresponding to an upper layer overlaps an under layer. In an exposureprocess performed on the upper layer, a shot is performed so as tocoincide with the under layer as much as possible based on an overlaymask of the under layer, thereby minimizing the overlay error. When theoverlay error is large (e.g., when a relative position differencebetween the under layer and the current layer is large) an adverseeffect may be exerted on the performance of a semiconductor device.

Referring to FIGS. 2A and 2B, a relative position difference a firstoverlay mark OM1 provided on a first layer 210, which is an under layer,and a second overlay mark OM2 provided on a second layer 220, which isan upper layer, may be measured may be calculated for calculating theoverlay error. The first overlay mark OM1 may be formed simultaneouslywhen a pattern is formed on the first layer 210, and the second overlaymark OM2 may be formed simultaneously when a pattern is formed on thesecond layer 220. An overlay mark may be formed in a box pattern shapeor a bar pattern shape, and may be formed on a scribe lane of a wafer.However, a shape or a position of the overlay mark is not limitedthereto.

FIG. 2B illustrates a semiconductor device provided on a semiconductorsubstrate 201. For example, a transistor TR including source/drainregions 202 and a gate electrode 210 g may be formed on thesemiconductor substrate 201, and a vertical contact 220 c connected tothe gate electrode 210 g may be formed. The gate electrode 210 g maycorrespond to a pattern provided on a first layer 210 which is an underlayer, and the vertical contact 220 c may correspond to a patternprovided on a second layer 220, which is an upper layer. When there isno overlay error, the vertical contact 220 c may be disposed in a centerportion of the gate electrode 210 g in a first direction (an xdirection). However, as illustrated in FIG. 2B, the gate electrode 210 gand the vertical contact 220 c may have a first overlay error OE1 in thefirst direction (the x direction) due to various causes. When the firstoverlay error OE1 is large, the vertical contact 220 c may deviate fromthe gate electrode 210 g and may be connected to the source/drain region202, or the vertical contact 220 c may overlap only a portion of thegate electrode 210 g and may be connected to the gate electrode 210 gand the source/drain region 202. A connection structure of the verticalcontact 220 c having the first overlay error OE1 may cause a severeerror such as an open defect and/or a short circuit defect.

Components of an overlay error may be variously differentiated from oneanother, and particularly, due to a hardware limitation of an EUVscanner or an EUV exposure apparatus, some of the components of theoverlay error is impossible to correct. For example, a K13 component ofthe overlay error may denote overlay distortion having athree-dimensional (3D) function shape in the x direction vertical to ascan direction, and in a conventional ArFi scanner, the K13 componentmay be corrected. However, the EUV scanner has a hardware (HW) structurewhich differs from that of the ArFi scanner, and thus, in the EUVscanner, a mirror has to largely move by about 100 mm to about 150 mm soas to compensate for the K13 component corresponding to a level of 0.5nm. Therefore, in the EUV exposure process, the K3 component of theoverlay error may be classified as a component impossible to correct.Various components of the overlay error will be described in more detailwith reference to FIGS. 3A to 3C.

The EUV exposure apparatus 100 according to the present exampleembodiment may heat a portion of at least one mirror of the projectionoptics 130 with the laser beam L2 by using the second illuminationoptics 150 of the laser apparatus LA, thereby minimizing an overlayerror caused by a non-uniform temperature distribution of a mirror inthe EUV exposure process. For example, the EUV exposure apparatus 100according to the present example embodiment may heat a portion of amirror, corresponding to a cause of a K13 component of overlay errorcomponents, of the projection optics 130 with the laser beam L2 by usingthe second illumination optics 150 of the laser apparatus LA, therebycorrecting the K13 component. In addition to the correction of the K13component, the other components of the overlay error may be correctedthrough a conventional method, thereby reducing or minimizing an overlayerror of the exposure target W.

FIGS. 3A to 3C are conceptual views for describing overlay components.

Referring to FIG. 3A, linear components corresponding to a first orderamong overlay error components are illustrated. For example, a K1component in a left and upper portion may denote a case where an overlayerror having a constant size occurs to one side in a first direction (anx direction), and a K2 component may denote a case where an overlayerror having a constant size occurs to one side in a second direction (ay direction). When the overlay error in the first direction (the xdirection) is referred to as dx and the overlay error in the seconddirection (the y direction) is referred to as dy, the K1 component maybe shown in a form of dx=k1, and the K2 component may be shown in a formof dy=k2. Here, the first direction (the x direction) may be a directionin which a slit disposed under the EUV mask M extends, and the seconddirection (the y direction) may correspond to a scan direction in theEUV exposure process and may be vertical to the first direction (the xdirection).

Moreover, a K3 component in a left and lower portion may denote a casewhere an overlay error having a size proportional to a position occursto both sides in the first direction (the x direction), and a K4component in a right and lower portion may denote a case where anoverlay error having a size proportional to a position occurs to bothsides in the second direction (the y direction). Therefore, the K3component may be shown in a form of dx=k3*x, and the K4 component may beshown in a form of dy=k4*y.

Linear components other than the K1 to K4 components may further includea K5 component (not shown) shown in a form of dx=k5*y and a K6 componentshown in a form of dy=k5*x.

Referring to FIG. 3B, linear components corresponding to a second orderamong overlay error components are illustrated. For example, a K7component in a left portion may denote a case where an overlay errorhaving a size proportional to the square of position occurs to bothsides in a first direction (an x direction), and a K8 component in aright portion may denote a case where an overlay error having a sizeproportional to the square of position occurs to both sides in a seconddirection (a y direction). Therefore, the K7 component may be shown in aform of dx=k7*x², and the K8 component may be shown in a form ofdy=k8*y².

Second-order components other than the K7 and K8 components may furtherinclude a K9 component (not shown) shown in a form of dx=k9*x*y, a K10component (not shown) shown in a form of dy=k10*y*x, a K11 component(not shown) shown in a form of dx=k11*y², and a K12 component (notshown) shown in a form of dy=k12*x².

Referring to FIG. 3C, linear components corresponding to a third orderamong overlay error components are illustrated. For example, a K13component in a left portion may denote a case where an overlay errorhaving a size proportional to position to the third power occurs to bothsides in a first direction (an x direction), and a K14 component in aright portion may denote a case where an overlay error having a sizeproportional to position to the third power occurs to both sides in asecond direction (a y direction). Therefore, the K13 component may beshown in a form of dx=k13*x³, and the K14 component may be shown in aform of dy=k14*y³.

Third-order components other than the K13 and K14 components may furtherinclude a K15 component (not shown) shown in a form of dx=k15*x²*y, aK16 component (not shown) shown in a form of dy=k16*y²*x, a K17component (not shown) shown in a form of dx=k17*x*y², a K18 component(not shown) shown in a form of dy=k18*y*x², a K19 component (not shown)shown in a form of dx=k19*y³, and a K20 component (not shown) shown in aform of dy=k20*x³.

The K1 to K19 components of the overlay error may be corrected throughphysical actuation in an ArFi exposure apparatus. Here, the physicalactuation may denote a method of providing pressure or tilt to a lens orquickly moving the lens. Further, a method of heating an exposure target(see W of FIG. 1) may be regarded as one of physical actuation methodsfor correcting an overlay error. Similarly to the ArFi exposureapparatus, the EUV exposure apparatus 100 may correct the K1 to K12components and the K14 to K19 components of the overlay error throughphysical actuation. However, as described above, due to an HW differencebetween the ArFi exposure apparatus and the EUV exposure apparatus 100,the EUV exposure apparatus 100 may hardly correct the K13 componentthrough physical actuation.

FIGS. 4A and 4B are a vector display diagram and a graph for describinga K13 component of an overlay error, respectively. In the graph of FIG.4B, the x axis represents a position (Pos.), the y axis represents asize (Err) of an overlay error, and a unit is an arbitrary unit (a.u.)showing only a relative size.

Referring to FIGS. 4A and 4B, a size and a direction of a vector 50 inFIG. 4A may denote a size and a direction of an overlay error caused bythe K13 component. For example, a size of an overlay error caused by theK13 component may increase in a direction away from a center in a firstdirection (an x direction). Further, the size of the overlay errorcaused by the K13 component may three-dimensionally increase withrespect to a position. That is, the size of the overlay error caused bythe K13 component may increase in proportion to position to the thirdpower.

FIG. 4B shows that the size of the overlay error caused by the K13component three-dimensionally increases with respect to a position. Forreference, a position on the x axis may correspond to a position in thefirst direction (the x direction) of FIG. 4A, and −7 and 7 portionswhere the overlay error is the maximum may be portions corresponding toboth sides of a rectangular shape S of FIG. 4A. The rectangular shape Sof FIG. 4A may be a shape corresponding to one shot in an exposureprocess. Therefore, the overlay error is the maximum in portionscorresponding to both sides in one shot, and is repeated in the same orsubstantially similar form in adjacent shots, as shown in FIG. 4B.

The overlay error caused by the K13 component illustrated in FIGS. 4Aand 4B may denote an overlay error which is measured between two layers(i.e., an under layer and a current layer) after the under layer isformed through the ArFi exposure process and the current layer, which isan upper layer, is formed through the EUV exposure process. Hereinafter,the overlay error may denote an overlay error between the under layerformed through the ArFi exposure process and the current layer formedthrough the EUV exposure process.

FIGS. 5A and 5B are a conceptual view showing a relationship between aK13 component of an overlay error and residual X (ResX) and a graphshowing a relationship between the K13 component and a residual budget,respectively. In FIG. 5B, the x axis represents a K13 component, the yaxis represents a residual budget R-B, and a unit of each of the K13component and the residual budget represents an arbitrary unit.

Referring to FIG. 5A, a left portion shows an example where a residual Xvalue is calculated without correcting the K13 component of the overlayerror, and a right portion shows an example where the exposure apparatus100 according to the present example embodiment corrects the K13component, and then the residual X value is calculated. Here, a residualmay denote an average overlay error value that is calculated after allcorrectable components among overlay error components are corrected, andthe residual X may denote an average overlay error value in a firstdirection (an x direction). In other words, the left portion shows anexample where the residual X is calculated under a condition where theK13 component is regarded as an uncorrectable component, and the rightportion shows an example where the residual X is calculated after theexposure apparatus 100 according to the present example embodimentcorrects the K13 component as a correctable component.

In each portion of a wafer W, an overlay error is illustrated as avector 90. In FIG. 5A, the vector 90 corresponding to the overlay erroris relatively large, but a large number of vectors 90 corresponding tooverlay errors may appear on the wafer W to have a very fine size. It isillustrated that, as the K13 component is corrected, a vector 90 on aright wafer W′ becomes smaller or is removed, and thus the residual Xmay be reduced from A to A-a. Therefore, the residual X may be improvedby correcting the K13 component. Further, when the K13 component islarge, a degree of improvement of the residual X based on correction ofthe K13 component may increase even further. A difference (for example,the a) of the residual X associated with the correction of the K13component may be referred to as an overlay penalty caused by the K13component or a residual budget.

Referring to FIG. 5B, as a value of the K13 component increases, theresidual budget may increase exponentially. An exposure apparatus and achuck each used in an EUV exposure process are differentiated from eachother and illustrated in a right box. That is, N and M are fordifferentiating EVU exposure apparatuses used in the EUV exposureprocess, and c1 and c2 are for differentiating chucks disposed in theEUV exposure apparatuses, respectively. As seen in the graph, it may beseen that a relationship between the K13 component and the residualbudget is irrelevant to the kinds of the EUV exposure apparatuses andthe chucks. Thus, when the K13 component is small, there is no problem,but when the K13 component increases, the residual budget may rapidlyincrease, thereby causing more defects of semiconductor devices in awafer and causing a considerable reduction in a yield rate.

FIG. 6 is a graph showing a K13 component variation of an overlay errorwith respect to a wafer based on a progress of an exposure process. InFIG. 6, the x axis represents numbers (Wafer #) of wafers in order inwhich an EUV exposure process is performed on the wafers in the same EUVexposure apparatus, they axis represents a K13 component of each of thewafers, and a unit may be an arbitrary unit.

Referring to FIG. 6, as a number of a wafer increases, the K13 componentmay increase. Here, a size of the K13 component may be determined as anabsolute value. An increase in the K13 component caused by an increasein a wafer number may be caused by non-uniform heating by EVU of mirrors(e.g., at least one mirror of projection optics) of the EUV exposureapparatus. In other words, mirrors of the projection optics (see 130 ofFIG. 1) may have a uniform temperature distribution when EUV exposurestarts. However, due to an illumination shape of EUV that isstructurized through reflection by the EUV mask M while the EUV exposureis being performed, non-uniform heating may occur in some regions of atleast one mirror of the projection optics 130. Therefore, acorresponding mirror may non-uniformly expand in each region and maycause a tilt defect and/or an aberration of a mirror surface, which maycause an overlay error having the K13 component. Further, as a wafernumber increases, such a phenomenon may increase more. Thus, as shown inthe graph, as a wafer number increases, the K13 component may increase.

FIGS. 7A and 7B are graphs showing an illumination shape of EUV by anEUV mask, a shape of EUV irradiated onto a mirror, and a temperatureprofile corresponding thereto. In the graph, the x axis represents aposition (Pos.) in a first direction (an x direction) corresponding to amirror, the y axis represents a temperature (Temp.), and a unit may bean arbitrary unit.

Referring to FIG. 7A, EUV reflected by an EUV mask (see M of FIG. 1) mayhave a dipole illumination shape I11 as illustrated. A hatched portion Pmay correspond to poles on which EUV concentrates. The dipoleillumination shape may enable a line and space (L/S) pattern to beeasily formed on an exposure target (see W of FIG. 1). The dipoles maybe disposed in the first direction (the x direction), but the presentexample embodiment is not limited thereto. In other example embodiments,the dipoles may be disposed in a second direction (a y direction) bychanging a shape of a pattern on the EUV mask M or by rotating the EUVmask M. Furthermore, the EUV may have various structurized illuminationshapes such as circular illumination, annular illumination, andquadrupole illumination by changing a shape of the pattern on the EUVmask M.

Referring to FIG. 7B, EUV having a dipole illumination shape may beirradiated onto at least one mirror (for example, the first mirror 132)of projection optics (see 130 of FIG. 1). In the first mirror 132, theEUV may have an illumination shape shown in FIG. 7B. In FIG. 7B, thefirst mirror 132 is illustrated in an elliptical shape, but the presentexample embodiment is not limited thereto. In other example embodiments,the first mirror 132 may have a circular shape. Further, a pole regionAp corresponding to a pole may have a circular shape or a shape the sameas or substantially similar to a shape of a dipole shown in FIG. 7A,instead of an elliptical shape.

As seen in a graph shown in a lower portion of FIG. 7B, a temperaturemay be high in the pole region Ap corresponding to the pole, and may below in a peripheral region Ab outside of the pole region Ap. Due to anillumination shape of a dipole reflected by the EUV mask M, the firstmirror 132 may have a non-uniform temperature distribution in eachregion thereof. Therefore, as described above, the first mirror 132 mayact as a cause of a K13 component of an overlay error. The presentexample embodiment is not limited to the dipole illumination shape, andthe first mirror 132 may have a non-uniform temperature distribution ineach region thereof due to various illumination shapes. Due to this, thefirst mirror 132 may act as the cause of the K13 component of theoverlay error.

FIGS. 8A to 8D are conceptual views of optical devices included in thesecond illumination optics 150 in the EUV exposure apparatus 100 of FIG.1.

Referring to FIG. 8A, an optical device 152 included in the secondillumination optics 150 may be implemented with L/S binary gratings. Theoptical device 152 having an L/S binary grating structure may process alaser beam of the laser source 140 in order for the laser beam to have adipole illumination shape. The optical device 152 may change an intervalbetween the L/S binary gratings to adjust an interval between dipoles ofdipole illumination. In some example embodiments, the optical device 152may rotate a direction in which the L/S binary gratings are arranged by,for example, 90 degrees, thereby allowing the dipoles of the dipoleillumination to be arranged in the second direction (the y direction).

Referring to FIG. 8B, an optical device 152 a included in the secondillumination optics 150 may be implemented with chess board (CB) binarygratings. The optical device 152 a having a CB binary grating structuremay process the laser beam of the laser source 140 in order for thelaser beam to have a quadrupole illumination shape. The optical device152 a may change an interval between the CB binary gratings to adjust aninterval between quadrupoles of quadrupole illumination. In some exampleembodiments, the optical device 152 a may rotate a direction in whichthe CB binary gratings are arranged by, for example, 45 degrees, therebyallowing the quadrupoles of the quadrupole illumination to be disposedin a 45-degree-rotated direction. In other example embodiments, theoptical device 152 a may be implemented with mesh binary gratings, andthe optical device 152 a may process the laser beam by using the meshbinary gratings in order for the laser beam to have a quadrupoleillumination shape.

In FIGS. 8A and 8B, two optical devices 152 and 152 a respectivelyhaving the L/S binary grating structure and the CB binary gratingstructure are illustrated, but a grating structure of an optical deviceis not limited thereto. For example, an optical device may beimplemented in various grating structures in addition to theabove-described grating structures, and process the laser beam of thelaser source 140 in order for the laser beam to have other various poleillumination shapes, based on the various grating structures.

Referring to FIG. 8C, an optical device 152 b included in the secondillumination optics 150 may be implemented as a slit plate including anopen region Op corresponding to a dipole. The laser beam of the lasersource 140 may pass through the optical device 152 b having a slit platestructure to have a dipole illumination shape. Two open regions Op maybe provided in the slit plate that is the optical device 152 b based ona dipole, but the position or number of open regions Op of the slitplate is not limited thereto. For example, the position or the number ofopen regions Op of the slit plate that is the optical device 152 b maybe variously changed based on a desired illumination shape of a laserbeam.

Referring to FIG. 8D, an optical device 152 c included in the secondillumination optics 150 may be implemented as a digital micro-mirrordevice (DMD). However, the optical device 152 c is not limited to a DMD,and may be implemented as another kind of spatial light modulator (SLM).For example, the optical device 152 c may be implemented as a gratinglight valve (GLV), an electro-optical device using lead (plomb)lanthanum zirconate titanate (PLZT), a ferroelectric liquid crystal(FLC), or the like.

The optical device 152 c having a DMD structure may include a devicesubstrate, a plurality of memory cells (for example, static randomaccess memory (SRAM) cells) provided on the device substrate, and aplurality of micro-mirrors MR which are arranged in a two-dimensional(2D) array structure on the memory cells. For example, the opticaldevice 152 c may include “1920*1080” micro-mirrors MR having the 2Darray structure. The arrangement and number of micro-mirrors MR are notlimited thereto. In other example embodiments, a material such asaluminum having a high reflectivity may be deposited on a surface ofeach of the micro-mirrors MR. For example, a reflectivity of each of themicro-mirrors MR may be 90% or more. Also, a lengthwise length and awidthwise length of each of the micro-mirrors MR may be the same as orsubstantially similar to each other and may each be several to tens μm.

When a digital signal is applied to the memory cell of the opticaldevice 152 c, each of the micro-mirrors MR may be inclined within acertain angle range with respect to a surface of the device substrate.For example, the certain angle range may be a range of ±12 degrees.However, a range of a slope is not limited to a range of ±12 degrees. Aslope of each of the micro-mirrors MR may be controlled, and thus, alaser beam incident on the optical device 152 c may be reflected in acertain direction, based on the slope of each of the micro-mirrors MR.Therefore, the laser beam may be processed to have various illuminationshapes, based on a selection of each of the micro-mirrors MR and may beirradiated onto at least one mirror (for example, a first mirror (see132 of FIG. 1) of the projection optics 130. In FIG. 8D, a hatchedportion represents a selected micro-mirror MR, and the laser beam of thelaser source 140 may be processed to have a dipole illumination shape byusing the selected micro-mirror MR. However, a shape of the laser beambased on processing by the optical device 152 c is not limited to thedipole illumination shape. In other example embodiments, byappropriately selecting at least one micro-mirror from among themicro-mirrors MR, the optical device 152 c may process the laser beam tohave various illumination shapes.

FIGS. 9A to 9C are conceptual views showing an illumination shape of alaser beam based on processing by the second illumination optics 150.

Referring to FIG. 9A, a laser beam of the laser source 140 may beprocessed by the second illumination optics 150 to have a circularillumination shape Ill1. A hatched portion P1 may correspond to aportion on which the laser beam concentrates. For example, the laserbeam may be processed by an optical device of the second illuminationoptics 150 to have the circular illumination shape Ill1. As describedabove with reference to FIGS. 8A to 8D, the optical device may beimplemented as, for example, a binary grating, a slit plate, or a DMD.For example, the optical device 152 b having a slit plate structurewhere one open hole Op is provided in a center thereof may process thelaser beam to have the circular illumination shape Ill1. In some exampleembodiments, the optical device 152 c having a DMD structure may processthe laser beam to have the circular illumination shape Ill1 byappropriately selecting at least one mirror from among the micro-mirrorsMR.

Referring to FIG. 9B, a laser beam of the laser source 140 may beprocessed by the second illumination optics 150 to have an annularillumination shape Ill2. A hatched portion P2 may correspond to aportion on which the laser beam concentrates. For example, the laserbeam may be processed by an optical device implemented as, for example,a binary grating, a slit plate, or a DMD to have the annularillumination shape Ill2 For example, the optical device 152 b having aslit plate structure where an open hole Op having an annular shape isprovided in an outer portion thereof may process the laser beam to havethe annular illumination shape Ill2 Also, by appropriately selecting atleast one micro-mirror from among the micro-mirrors MR, the opticaldevice 152 c having a DMD structure may process the laser beam to havethe annular illumination shape Ill2 Furthermore, the laser beam may beprocessed to have an annular illumination shape having two or morerings, based on a grating structure such as a circular zone plate.

Referring to FIG. 9C, a laser beam of the laser source 140 may beprocessed by the second illumination optics 150 to have a quadrupoleillumination shape Ill3. A hatched portion P3 may correspond to a poleon which the laser beam concentrates. For example, the laser beam may beprocessed by an optical device implemented as, for example, a binarygrating, a slit plate, or a DMD to have the quadrupole illuminationshape Ill3. For example, the optical device 152 b having a slit platestructure where four open holes Op corresponding to a quadrupole isprovided in an outer portion thereof may process the laser beam to havethe quadrupole illumination shape Ill3. In some example embodiments, theoptical device 152 c having a DMD structure may process the laser beamto have the quadrupole illumination shape Ill3 by appropriatelyselecting at least one micro-mirror from among the micro-mirrors MR.Furthermore, the optical device 152 a having a CB binary gratingstructure or a mesh binary grating structure may process the laser beamto have the quadrupole illumination shape Ill3.

According to some example embodiments, the laser beam of the lasersource 140 may be processed by the second illumination optics 150 tocorrespond to an illumination shape of EUV structurized throughreflection by the EUV mask M. For example, in a case where the EUV isstructurized through reflection by the EUV mask M to have a dipoleillumination shape, the laser beam may be processed by the secondillumination optics 150 to have the dipole illumination shape. In a casewhere the EUV is structurized through reflection by the EUV mask M tohave a quadrupole illumination shape, the laser beam may be processed bythe second illumination optics 150 to have the quadrupole illuminationshape.

According to some example embodiments, the laser beam of the lasersource 140 may be processed by the second illumination optics 150 tohave an illumination shape that is opposite to (e.g., a negative shapeof) an illumination shape of the EUV structurized through reflection bythe EUV mask M. For example, in a case where the EUV is structurizedthrough reflection by the EUV mask M to have the dipole illuminationshape, the laser beam may be processed by the second illumination optics150 to have an illumination shape where light concentrates on a regionaround a dipole.

FIGS. 10A to 10D are conceptual views for describing the principle ofheating a mirror with a laser beam in the EUV exposure apparatus 100 ofFIG. 1.

Referring to FIGS. 10A to 10D, a temperature sensor 170 may be disposedon a rear surface of at least one mirror (for example, the first mirror132) of the projection optics 130. Also, the EUV L1 of the EUV source110 and the laser beam L2 of the laser source 140 may be simultaneouslyor sequentially irradiated onto the first mirror 132. The laser beam L2having appropriate energy may be irradiated onto an appropriate positionof the first mirror 132 based on temperature information about the firstmirror 132 obtained by the temperature sensor 170 and a desired amountof energy or a temperature distribution of the first mirror 132 based onthe temperature information.

For example, in a state where the laser beam L2 is not irradiated, atemperature distribution of the first mirror 132 is shown as in a graphof the lower portion of FIG. 10B, and a K13 component of an overlayerror occurs due to the temperature distribution of the first mirror132. In this case, the second illumination optics 150 may process thelaser beam L2 to have an illumination shape (e.g., an illumination shapewhere the laser beam L2 concentrates on a peripheral region Ab otherthan a pole region Ap) which is opposite to (e.g., a negative shape of)the dipole illumination shape, and by heating the first mirror 132 withthe laser beam L2 having the illumination shape, an entire temperaturedistribution of the first mirror 132 may be uniform as shown in a graphof the lower portion of FIG. 10C. Accordingly, the K13 component of theoverlay error that occurs due to an EUV concentration on the pole regionAP may be corrected.

Moreover, the K13 component of the overlay error may occur due to acause different from the above-described cause. For example, in a casewhere the EUV exposure apparatus 100 is set to maintain a certaintemperature difference between the peripheral region Ab and the poleregion Ap of the first mirror 132 considering the K13 component of theoverlay error, a desired temperature difference is not maintained (e.g.,the amount of EUV concentrating on the pole region Ap may beinsufficient), and thus the K13 component of the overlay error mayoccur. In this case, the second illumination optics 150 may process thelaser beam L2 to have a dipole illumination shape, and by heating thefirst mirror 132 with the laser beam L2 having the dipole illuminationshape, the temperature difference between the peripheral region Ab andthe pole region Ap of the first mirror 132 may increase to a desiredlevel. Accordingly, the K13 component of the overlay error that occursbecause the EUV concentrating on the pole region AP is insufficient maybe corrected.

Hereinabove, correction performed on the K13 component of the overlayerror has been described above, but by irradiating a laser beam onto atleast one mirror of a projection optics to heat the at least one mirrormay correct other components of the overlay error that is different fromthe K13 component. A correction method (for example, a physicalactuation method) of correcting the other components, other than the K13component, of the overlay error may be installed in the EUV exposureapparatus 100, and the other components, other than the K13 component,of the overlay error may be sufficiently corrected by the physicalactuation method. Therefore, in a case where the EUV exposure apparatus100 is designed to perform the physical actuation method on the othercomponents of the overlay error, a correction method of heating a mirrorwith a laser beam may be omitted on the other components of the overlayerror. However, in some example embodiments, the other components of theoverlay error may be corrected by simultaneously performing the physicalactuation method and the correction method of heating the mirror withthe laser beam.

FIGS. 11 and 12 are flowcharts illustrating procedures of an EUVexposure method according to some example embodiments. Hereinafter, theEUV exposure method according to the present example embodiment will bedescribed with reference to FIGS. 11 and 12 in conjunction with FIG. 1,and descriptions given above with reference to FIGS. 1 to 10D will bebriefly given or will be omitted.

Referring to FIG. 11, in the EUV exposure method according to thepresent example embodiment, the EUV source 110 may first generate andoutput the EUV L1 in operation S110. The EUV L1 may have, for example, ahigh energy density within a wavelength range of about 5 nm to about 50nm. For example, in the EUV exposure method according to the presentexample embodiment, the EUV L1 may have, for example, a high energydensity corresponding to a wavelength of 13.5 nm.

Subsequently, in operation S120, the first illumination optics 120 maytransfer the EUV L1 to the EUV mask M. A plurality of mirrors includedin the first illumination optics 120 may reflect the EUV L1 to allow theEUV L1 to be incident on the EUV mask M.

Subsequently, in operation S130, the projection optics 130 may projectthe EUV L1, reflected by the EUV mask, onto the wafer W which is theexposure target W. The EUV L1 may be structurized in a certainillumination shape through reflection by the EUV mask M, based on apattern on the EUV mask M. The EUV L1 having the certain illuminationshape may non-uniformly heat at least one mirror (for example, the firstmirror 132) of the projection optics 130, and due to this, a temperaturedistribution of the first mirror 132 may be non-uniform, causing anexposure defect and a K13 component of an overlay error. Projection ofthe EUV L1 by the projection optics 130 onto the wafer W may denoteprojection of the EUV L1 onto a photoresist on the wafer W.

Subsequently, in operation S135, whether to correct the K13 component ofthe overlay error may be determined. Whether to correct the K13component of the overlay error may be determined based on whether theK13 component of the overlay error exceeds a threshold or predeterminedcriterion.

When the K13 component of the overlay error does not need to becorrected (No), the EUV exposure method may end.

Otherwise, when the K13 component of the overlay error need to becorrected (Yes), the laser source 140 may generate and output the laserbeam L2 for heating in operation S140. The laser beam L2 may be, forexample, an IR laser beam or an UV laser beam. However, a kind of thelaser beam L is not limited thereto. For example, the laser beam L2 maybe a laser beam L2 having a wavelength which does not change chemicalproperties of the photoresist on the waver W which is the exposuretarget W.

Subsequently, in operation S150, the second illumination optics 150 mayirradiate the laser beam L2 onto a mirror of the projection optics 130.The laser beam L2 may be processed by the second illumination optics 150to have various illumination shapes. That is, the laser beam L2 may beprocessed by an optical device, such as a binary grating, a slit plate,or a DMD, of the second illumination optics 150 to have variousillumination shapes such as dipole illumination, quadrupoleillumination, circular illumination, and annular illumination. The laserbeam L2 may have an illumination shape corresponding to a portion, whichis to be heated, of a mirror onto which the laser beam L2 is irradiated.For example, in a case where the EUV L1 having the dipole illuminationshape is irradiated onto a mirror and the laser beam L2 has to beirradiated onto a region other than two pole regions, the laser beam L2may be processed by the second illumination optics 150 to have anillumination shape where light concentrates on a region around a dipole.

After operation S150 of irradiating the laser beam L2 onto the mirror,the EUV exposure method may end. According to some example embodiments,whether to perform an exposure process on another wafer may bedetermined before the EUV exposure method ends, and when the exposureprocess performed on the other wafer is not needed, the EUV exposuremethod may end.

Referring to FIG. 12, the EUV exposure method according to the presentexample embodiment may be similar to the EUV exposure method of FIG. 11.However, the EUV exposure method according to the present exampleembodiment may further include operation S137 of measuring, by using thetemperature sensor 170, a temperature of a portion or an entirety of themirror and operation S139 of calculating the amount of energy which isto be applied to the mirror, between operation S135 of determiningwhether to correct the K13 component and operation S140 of generatingand outputting the laser beam L2.

In operation S137 of measuring a temperature, the amount of energyapplied to the mirror (for example, the first mirror 132) by the EUV L1or a region-based temperature distribution of the first mirror 132 maybe calculated based on temperature information obtained through thetemperature sensor 170. Also, in operation S139 of calculating theamount of energy, positions of regions of the first mirror 132 to whichenergy is to be applied may be determined, and the amount of energywhich is to be applied to a corresponding position by the laser beam L2may be calculated. Subsequently, in operation S150 of irradiating thelaser beam L2 onto the mirror, the laser beam L2 may be processed by thesecond illumination optics 150, and the laser beam L2 having anappropriate amount of energy may be irradiated onto desired regions ofthe first mirror 132.

FIG. 13 is a flowchart illustrating a procedure of a method ofmanufacturing a semiconductor device by using the exposure method ofFIG. 11. Hereinafter, the EUV exposure method according to the presentexample embodiment will be described with reference to FIG. 13 inconjunction with FIG. 1, and descriptions given above with reference toFIGS. 11 and 12 will be briefly given or will be omitted.

Referring to FIG. 13, the exposure method of FIG. 11 may be performed.For example, operations S210 to S250 including operation S210 ofgenerating and outputting the EUV L1 to operation S250 of irradiatingthe laser beam L1 onto the mirror may be performed. The method ofmanufacturing a semiconductor device according to the present exampleembodiment may perform the exposure method of FIG. 12 instead of theexposure method of FIG. 11.

Subsequently, in operation S260, the wafer W (e.g., the exposure targetW) may be patterned based on exposure. Here, the exposure may correspondto operation S230 of irradiating the EVU L1 onto the wafer W. Asdescribed above, projection of the EUV L1 onto the wafer W may denote anoperation of irradiating the EUV L1 onto a pattern material (for examplea photoresist) coated on the wafer W. After an exposure process based onthe exposure method of FIG. 11, a real pattern which is to be formed onthe wafer W may be formed through a develop process and an etch process.

Subsequently, in operation S270, a subsequent semiconductor process maybe performed on the wafer W. The subsequent semiconductor process mayinclude various processes. For example, the subsequent semiconductorprocess may include a deposition process, an etch process, an ionprocess, a cleaning process, etc. Also, the subsequent semiconductorprocess may include a singulation process of individualizing the wafer Winto semiconductor chips, a test process of testing the semiconductorchips, and a packaging process of packaging the semiconductor chips. Asemiconductor device may be finished through the subsequentsemiconductor process performed on the wafer W.

In the method of manufacturing a semiconductor device by using theexposure method according to the present example embodiment, an optimalexposure process of minimizing an overlay error may be performed basedon a method of heating a portion of a mirror with the laser beam L2, andthus, a semiconductor device which is low in error rate and is enhancedin reliability may be manufactured, thereby considerably enhancing ayield rate.

As described above, the EUV exposure apparatus and the exposure methodaccording to the example embodiments may heat at least one mirror of theprojection optics with a laser beam by using the laser apparatus,thereby minimizing an overlay error caused by the mirror. For example,the EUV exposure apparatus and the exposure method according to theexample embodiments may heat a portion of the at least one mirror of theprojection optics with the laser beam by using the illumination opticsof the laser apparatus, thereby minimizing an overlay error caused by anon-uniform temperature distribution of the mirror in the EUV exposureprocess.

Moreover, in the method of manufacturing a semiconductor device by usingthe exposure method according to the example embodiments, the optimalexposure process for minimizing an overlay error may be performed basedon a method of heating a portion of the mirror with the laser beam in anexposure step, and thus, a semiconductor device which is low in errorrate and is enhanced in reliability may be manufactured, therebyconsiderably enhancing a yield rate.

While the inventive concepts have been particularly shown and describedwith reference to embodiments thereof, it will be understood thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the following claims.

1.-15. (canceled)
 16. An extreme ultraviolet (EUV) exposure methodcomprising: generating and outputting, by using an EUV source, EUV;transferring, by using first illumination optics, the EUV to an EUVmask; projecting, by using projection optics, the EUV reflected from theEUV mask onto an exposure target; generating and outputting, by usinglaser apparatus, a laser beam; forming, by using second illuminationoptics, an illumination shape of the laser beam; and irradiating thelaser beam having the illumination shape onto at least one mirrorincluded in the projection optics.
 17. The EUV exposure method of claim16, wherein the irradiating the laser beam comprises heating, by usingthe laser apparatus, a portion of the at least one mirror through thesecond illumination optics.
 18. The EUV exposure method of claim 16,further comprising: before the generating and outputting of the laserbeam, measuring, by using a temperature sensor attached on a rearsurface of the at least one mirror, a temperature of a portion or anentirety of the at least one mirror; and calculating an amount of energyto be applied to the at least one mirror based on the measuredtemperature, wherein the irradiating the laser beam comprisesirradiating the laser beam having the calculated amount of energy to theat least one mirror by using the laser apparatus.
 19. The EUV exposuremethod of claim 18, wherein the calculating an amount of energycomprises determining a first portion of the at least one mirror, thefirst portion being a portion to which the laser beam is to be applied,and the irradiating the laser beam comprises irradiating the laser beamonto the determined first portion through the second illumination opticsby using the laser apparatus.
 20. The EUV exposure method of claim 16,wherein the irradiating the laser beam comprises forming theillumination shape of the laser beam by using at least one of a binarygrating, a slit plate, or a digital micro-mirror device (DMD) by usingthe second illumination optics and the forming an illumination shape ofthe laser beam comprises at least one of processing the laser beam toform the illumination shape to be one of circular illumination, annularillumination, dipole illumination, or quadrupole illumination, orprocessing the laser beam to form the illumination shape to have anegative shape of one of the circular illumination, the annularillumination, the dipole illumination, or the quadrupole illumination.21. The EUV exposure method of claim 16, wherein the irradiating thelaser beam comprises heating, by using the laser beam, a first portionand a second portion of the at least one mirror through the secondillumination optics to compensate for a component of an overlay errorbetween layers of the exposure target, the first portion being oneportion of the at least one mirror, the second portion being anotherportion of the at least one mirror that is other than the first portion,when an error associated with the component three-dimensionallyincreases as a position distances from a center to both sides in a firstdirection, the first direction being perpendicular to a scan directionin an exposure process.
 22. A method of manufacturing a semiconductordevice, the method comprising: generating and outputting, by using anextreme ultraviolet (EUV) source, EUV; transferring, by using firstillumination optics, the EUV to an EUV mask; projecting, by usingprojection optics, the EUV reflected from the EUV mask onto a wafer, thewafer being an exposure target; generating and outputting, by usinglaser apparatus, a laser beam; forming, by using second illuminationoptics, an illumination shape of the laser beam; irradiating the laserbeam having the illumination shape onto at least one mirror included inthe projection optics; patterning the wafer; and performing a subsequentsemiconductor process on the wafer.
 23. The method of claim 22, whereinthe irradiating the laser beam comprises heating a portion of the atleast one mirror through the second illumination optics by using thelaser apparatus.
 24. The method of claim 22, wherein the irradiating thelaser beam comprises calculating an amount of energy to be applied tothe at least one mirror by using a temperature sensor attached on a rearsurface of the at least one mirror.
 25. The method of claim 22, whereinthe irradiating the laser beam comprises: determining a first portion byusing a temperature sensor attached on a rear surface of the at leastone mirror, the first portion being a portion to which the laser beam isto be applied; and calculating an amount of energy to be applied to thefirst portion.